>She was asking who the first Homo Sapiens was. I suggested that if there was such a person, if an anthropologist had been there they wouldn’t have seen anything special happening.

There is no such person. Speciation isn't some quick and dramatic happening, it's a generally slow evolution (though a lot faster for things like bacteria). "Species" is just how biologists categorize things, but organisms are continually evolving to some extent, so if you grab some random humans from 1M years ago, and compare them to random humans today, you'll find some pretty significant differences most likely, even if it is possible for them all to interbreed. If you go back even farther, the differences will be greater, you might not be able to interbreed, but there's no clear delineation if you look at humans and their ancestors over the course of the last ~5M years, just a slow progression. Our modern biologists/anthropologists make up names for the beings from various select points in time, since they do differ markedly from beings at other far-removed points in time, but we don't have a clear picture anyway because all we have is fossils which don't show a clear picture, they're just select points in time where we got lucky and were able to find an artifact.

Continuity existing between separate categories doesn't mean categories are arbitrary nor artifacts of language. For example adults and children really are separate categories for many important purposes yet there is never a single day when a child becomes an adult.

That's an excellent analogy. How a society differentiates adults and children, is often more a reflection of societal norms than it is an objective biological distinction.

Similarly, analyses like these cannot help but be a reflection of the society that produced them. This article features a callout in the middle with weirdly axis-ed charts about climate change, inequality and environmental degradation, it's difficult not smirk knowing that within the context of our current society, there was no way it could be otherwise. One wonders 50 or 150 years ago what the cultural bugbears were and what the callout in the middle of the page would have featured. Overpopulation? Nuclear war? Out-of-wedlock births?

It's a decent analogy, but not a great one. Most people grow up in a fairly similar way. Every civilisation develops differently. Also, it's clear where one person ends and the next person begins. With civilisations, that's not so clear.

Categorizations can be useful definitely, but we need to bear in mind they’re not definitive or absolute. The underlying reality is primary, not the categorization, but it’s easy to get it the wrong way round.